Tag: annelids

Conservation and nameless earthworms: Assessors in the dark?

Species that live exclusively in a single region are at a particular risk of extinction. However, for them to be protected, thorough assessments of the environmental impacts need to be performed.

There are more than 100 earthworm species living in the soil and dead wood of KwaZulu-Natal Province, South Africa. Most of them live exclusively in small regions in the province, which makes them extremely vulnerable.

To scientists Dr Adrian J. Armstrong, Ezemvelo KZN Wildlife, and Ms Thembeka Nxele, KwaZulu-Natal Museum, the problem is twofold. Firstly, they note that the expression “out of sight, out of mind” is very suitable for the case of the endemic earthworms in South Africa. Secondly, they point out that the lack of common names for these species is a stumbling block that hinders their inclusion in conservation assessments.

As a result, the researchers try to rectify this situation by assigning standardised English names to the endemic earthworms in KwaZulu-Natal. Their article is published in the open access journal African Invertebrates.

Scientific names are often intractable to non-specialists, and the lack of common names leaves environmental assessors in the dark when they need to figure out which earthworms may occur at a development site. In the meantime, it has been found that about 50% of the native vegetation in KwaZulu-Natal has already been removed as a result of infrastructure construction and the figure is rising.

“The indigenous earthworms generally don’t survive in developed areas,” say the authors.

For instance, the informal use of an English name (green giant wrinkled earthworm) for the species Microchaetus papillatus, has facilitated the inclusion of this species in environmental impact assessments in KwaZulu-Natal.

While the green giant wrinkled earthworm does occur in a relatively large and rapidly developing area in KwaZulu-Natal, other species live in smaller areas that have been urbanised even more.

The extinction of these earthworms is not only undesirable from the point of view of biodiversity advocates – the role of this group of soil organisms is impossible to replace fully with non-native earthworms. For example, some of the large indigenous earthworms (more than 1 m in length) burrow much deeper than the non-native species, thereby enriching and aerating the soil at greater depth.

The authors are hopeful that by giving the indigenous earthworms in KwaZulu-Natal common names, the threatened and endemic species will be conserved through inclusion in environmental impact assessments. Furthermore, they believe that earthworms could draw attention to the areas where they occur whenever a choice for new protected areas is to be made.

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Original source:

Armstrong AJ, Nxele TC (2017) English names of the megadrile earthworms (Oligochaeta) of KwaZulu-Natal. African Invertebrates 58(2): 11-20. https://doi.org/10.3897/AfrInvertebr.58.13226

Unfamiliar bloodline: New family for an earthworm genus with exclusive circulatory system

New earthworm family, named Kazimierzidae, has been established for a South African indigenous genus of 21 species. Although the circulatory system in the group has been regarded as exclusive upon their original description in 2006, their raising to a family status have only recently been confirmed by a research team from South Africa.

Scientists Mrs Thembeka Nxele, Dr Danuta Plisko (original discoverer of the genus Kazimierzus, now known as family Kazimierzidae), affiliated with Natal Museum (NMSA), Oliver Tendayi Zishiri, affiliated with University of KwaZulu-Natal, and Dr Taro Mwabvu, University of Mpumalanga, looked into the earthworm collection at the NMSA, as well as the type material and the available literature. Their study is published in the open access journal African Invertebrates.

When compared to the rest of the members in the family Microchaetidae, where the former genus had been placed, the studied earthworms show a number of distinct characters, including an “exclusive” circulatory system. In these species it is a simple single tube stretching along the whole body.

All 21 earthworm species, now members of the newly established family, can only be found in small areas restricted in the western and south-western Atlantic coast of South Africa. These locations have long been known for their endemic invertebrates and diverse flora.

In their paper, the authors note that it is actually the restricted range, and therefore the specific ecological requirements, that might have led these earthworms to become that different from other species. Their distribution and, hence, poor dispersal ability, are also the reason why the newly established group would be particularly vulnerable if the habitat is transformed.

“The species distribution of earthworms in Southern Africa is presently poorly known hence the urgency for extended study on earthworm diversity and their distribution patterns,” point out the scientists. “Extensive earthworm collection in the western Atlantic coast may bring more data on this and other taxa.”

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Original source:

Nxele TC, Plisko JD, Mwabvu T, Zishiri TO (2016) A new family Kazimierzidae for the genus Kazimierzus, earlier recorded to the composite Microchaetidae (Annelida, Oligochaeta). African Invertebrates 57(2): 111-117. doi: 10.3897/AfrInvertebr.57.10042